The invention relates to the art of digital counting and more particularly to a counter/timer having incremental indicators.
The invention is particularly applicable for use as a timer and it will be described with reference thereto; however, it is appreciated that the invention relates generally to a digital counting device which may be used both as a counter and a timer.
In controlling processes and machines, there has been developed a wide range of counters and timers which control various functions. These counters or timers generally include an arrangement for changing the counts or time which constitute a complete cycle. Until the last decade or so, these counters or timers were motor driven electromechanical devices which generally included a dial having a first pointer which could be adjusted to the desired time or count, known as the set point, and a second pointer which progressed toward the set point pointer. Consequently, visual inspection easily indicated the progress of a timer or counter as it was being cycled. The spacing of the movable or progress pointer with respect to the set point pointer indicated the amount of the cycle which had expired or, conversely, the amount of the cycle which was remaining. This information is often valuable for an operator monitoring the process or machine being controlled by the timer or counter. With the advent of solid state devices, such as the MOS and CMOS technology, many of the industrial counters and timers have been converted to digital devices using solid state counting circuits. In these devices, thumbwheel units were often provided to set the desired cycle or set point. The thumbwheel units would include visible digits which would indicate to the operator the cycle being counted or timed. Often by the use of display devices, such as 7-Bar indicators, the progress of the solid state timer toward the set point of the thumbwheel units was made visually available to an operator. In such devices, thumbwheel units would indicate the preselected cycle and a readout or display device would display the current condition of the device. The use of a display device presented some difficulty. The operator had to compare mentally the readout or display device with the thumbwheel setting to determine the progress of the counter or timer through its preselected cycle.
In order to render the timer or counter less expensive, the digital decoder circuits and the display devices associated therewith were sometimes eliminated so that only the thumbwheel settings were visible. A light on the digital device would indicate that the device was cycled. In this type of device, there was no manner for the operator to determine the portion of the cycle which had expired or which remained. Consequently, there was some sales resistance to the removal of the decoders and readout devices for counters or timers. It was found that the decoder and display arrangement for the counter or timer contributed substantially to the total cost of the device. For that reason, there is a substantial demand for a counter or timer which will indicate the progression of a digital counter or timer through its cycle without the expense concomitant with the previously used digital decoders and display devices or units.